Brushless DC motors in which permanent magnets are located on the rotor surface are already known. These permanent magnets are usually produced as ring magnets. When such permanent magnets are arranged on the rotor surface, a return path body which is firmly connected to the rotor shaft is provided between the rotor shaft and the permanent magnets. The annular permanent magnets are adhesively bonded to this return path body so that a torque can be transmitted to the rotor shaft via the return path body. The width of the adhesive gap between the ring magnet and the return path body has to comply with an upper and lower limit in order to provide optimum adhesive bonding. This adhesive bonding should be performed in such a way that the ring magnet sits centrally, in order to prevent any imbalance. To this end, a complicated adhesive bonding apparatus is usually provided which is to be fitted with the components to be adhesively bonded.
DE 103 14 394 A1 discloses a rotor for a brushless DC motor and a method for mounting a rotor of this type. This known rotor has a shaft, a return path body which is arranged on the shaft, and a ring magnet which surrounds the return path body. A gap is formed in the axially running region between the return path body and the ring magnet. Furthermore, a retaining element is provided which, outside the gap, is connected at one end to the shaft or to the return path body and at the other end to the ring magnet. This retaining element connects the ring magnet to the shaft or to the return path body in a force-fitting manner and additionally centers said ring magnet with respect to the shaft or the return path body. Furthermore, a casing which surrounds the ring magnet is preferably provided. The retaining element and the casing are integrally formed as a sleeve, with the ring magnet being connected to the sleeve in a force-fitting manner by being pressed into said sleeve. In the case of this known rotor, the ring magnet is arranged centrally with respect to the rotor shaft or the return path body, without adhesive bonding being required.